Traditional endodontic files consist of a tapered cutting flute portion having a shaft connected to a handle that is gripped by a user such as, for example, a dentist or an endodontist. Endodontic files are used to remove the contents of a root canal and to prepare and/or shape the root canal prior to filling it. Endodontic files are also used to determine the length of the root canal by connecting an electronic apex locator to the endodontic file. An electronic apex locator is an electronic measuring device used to determine the length of root canals.
FIG. 1 shows a traditional endodontic file 10 with tapered cutting flutes 12 located at one end of a shaft 14 secured to a handle 16 that is grasped by a user to perform the root canal procedure. Typically, shaft 14 is connected to an apical end 18 of handle 16 and the user grasps handle 16 to perform the root canal procedure.
As seen in FIG. 2, an electronic apex locator (not shown) is connected to the endodontic file 10 by an electrically conductive clip or other mechanism 22 attached to shaft 14 between tapered cutting flutes 12 and handle 16 in order to measure the length of the root canal. Clip 22 is connected to the apex locator by an electrically conductive wire 23 and tapered cutting flutes 12 and shaft portion 14 are made of an electrically conductive material so that electrical signals can be sent from tapered cutting flutes 12 to the apex locator. One problem of the assembly shown in FIG. 2 is that clip 22 is typically attached to shaft 14 between tapered cutting flutes 12 and handle 16 forming a 90° angle lever on shaft 14.
This location of attachment of clip 22 to shaft 14 is undesirable because it impairs visibility. Additionally, unwanted lateral forces may be imparted to shaft 14. Such forces impair the dexterity of file manipulation and impair the angle of file insertion into the root canal. Furthermore, attaching the electronic apex locator to shaft 14 prevents the use of an electrical insulating sheath on shaft 14.
Endodontic instruments are also shown in described in U.S. Pat. No. 4,260,379 (Groves et al.), U.S. Pat. No. 4,332,561 (McSpadden), U.S. Pat. No. 4,824,369 (Levy), U.S. Pat. No. 5,112,224 (Shirota), U.S. Pat. No. 5,213,499 (Levy), and U.S. Pat. No. 5,775,903 (Atkins), and Buchanan (U.S. Pat. No. 4,836,780), the entire disclosures of which patents are hereby incorporated by reference as if set forth in their entirety for all purposes.